Table 1. NDH-F antibody binding to thylakoid membranes.

Freshly isolated thylakoids (0.5 μg of Chl·μl⁻¹) were incubated with preimmune antiserum for 20 min at 20 °C, washed twice with 10 mM Tricine (pH 8.0) and 140 mM NaCl (wash buffer) and then incubated with monospecific anti-NDH-F. After two washings with wash buffer, thylakoids were incubated with goat anti-rabbit IgG conjugated with alkaline phosphatase (AP–anti-rabbit IgG) for 20 min at 20 °C and then washed twice with the wash buffer. The immunocomplexes were quantified by measuring alkaline phosphatase activity conjugated with the goat anti-rabbit IgG. Where indicated, no NDH-F antibody was added (treatment 2) or thylakoids were subjected to trypsin digestion [360 units·(mg of Chl)⁻¹] for 20 min at 4 °C before preimmune antiserum (treatment 3) or after NDH-F antibody (treatment 4) incubation. One unit of alkaline phosphatase hydrolyses 1 μmol of p-nitrophenyl phosphate per min at 37 °C. Values in parentheses represent S.D., n=4.

Treatment	Phosphatase activity [units·(mg of Chl)−1]
1. Preimmune serum→anti-NDH-F→AP–anti-rabbit IgG	7.1 (0.5)
2. Preimmune serum→AP–anti-rabbit IgG	3.8 (0.1)
3. Trypsin→preimmune serum→anti-NDH-F→AP–anti-rabbit IgG	3.6 (0.3)
4. Preimmune serum→anti-NDH-F→trypsin→AP–anti-rabbit IgG	8.0 (0.3)